Coating compositions used in the original automotive equipment market are being called to more and more stringent performance requirements. Coating systems are expected to provide lasting weatherability, durability, resistance to acid etching, and mar resistance, while maintaining outstanding appearance properties. Coating systems used in certain applications, such as on plastic substrates, must also be flexible. Additionally, automotive coating compositions are expected to be available in environmentally friendly formulations.
Some coating compositions cured via acid-epoxy cure mechanisms, while providing excellent acid etch resistance, offer only marginal mar resistance. Conventional coating compositions cured with aminoplast crosslinking agents have been known for superior durability, but it has only been recently that aminoplast-cured coatings providing acid etch resistance have become available. Moreover, aminoplast-cured systems typically suffer from high photo-oxidation rates due to the breakdown of the aminotriazine ring inherently found in most aminoplast resins. Such degradation is due to prolonged exposure to ultraviolet light.
It would be desirable to provide crosslinking agents and curable compositions suitable for use as film-forming compositions in the automotive and industrial markets that overcome the drawbacks of the prior art, providing both appearance and performance properties now considered essential in automotive applications.